Snapchat’s worldwide ad revenues set to slow, research says

Snapchat's advertising revenues are likely to slow this year, with the photo-sharing app set to make $774.1 million, down from a predicted $935.5 million a year ago.

Most of this revenue, some $642.5 million, will come from the U.S., according to a report by eMarketer. That figure is down from the $770 million forecast by the research company in March.

Of those joining the platform in the U.S., many are older than you might think.

"More than 50 percent of our daily new users in the U.S. are over the age of 25. I think that's something really key that marketers should be aware of," James Borow, director of revenue programs at Snap, told eMarketer.

Marketers have expressed mixed feelings about Snapchat, with ad agencies telling CNBC in August that interest in the platform is flat to dwindling.

Meanwhile, Martin Sorrell, chief executive of the world's largest ad agency group WPP, said his company would spend $200 million on Snapchat on behalf of clients this year, double its spend in 2016. But Sorrell called this figure "a flea on the elephant's backside" compared to Facebook, on which it will spend more than $2 billion in 2017.

The average time people in the U.S. spend on Snapchat versus Instagram is neck-and-neck, according to eMarketer predictions. Users spent 16 minutes a day on Snapchat in 2014 with that figure set to increase to 28 minutes in 2019. Time spent on Instagram is set to rise to 27 minutes in 2019, from 18 minutes in 2014.

The rivalry between Snapchat and Instagram is hotting up. Instagram launched Stories in August 2016, a Snapchat-like feature where pictures and video disappear after 24 hours, while last month Burger King and U.K. grocery store Sainsbury's said they were the first advertisers to film an ad using Snapchat Spectacles.

A representative for Snapchat was not immediately available for comment.